1. Field of the Invention
The present invention relates to a pressure-contact terminal including pressure-contact blades to be pressure-contacted with a covered electrical wire and a method for connecting a pressure-contact terminal to a covered electric wire.
2. Description of the Related Art
FIG. 6 is a perspective view of a conventional pressure-contact terminal which is disclosed in Japanese Utility Model Unexamined Publication No. Hei. 7-22468. This pressure-contact terminal includes a contact portion 1 into which a mating terminal is inserted, a pressure-contact portion 2 with which a covered electric wire can be pressure-contacted, and a clamping portion 3 for fixing the covered electric wire. The pressure-contact portion 2 includes a pair of pressure-contact blades 5 which are provided in a pair of right and left side wall portions 4 thereof respectively; that is, if a covered electric wire is inserted into between the two side wall portions 4, then the two pressure-contact blades 5 respectively bite the covering portion of the covered electric wire inserted and can be thereby contacted with a core embedded in the covered electric wire, so that the pressure-contact portion 2 or the pressure-contact terminal is allowed to conduct. In this structure, as described above, because the covered electric wire is inserted between and is pressure-contacted with the pressure-contact blades 5, a gap between the pressure-contact blades 5 (which is generally referred to as a pressure-contact slot) can be spread out easily, and such spread-out of the pressure-contact blades 5 results in the poor contact of the pressure-contact blades 5 with respect to the core of the covered electric wire. In view of this, in the present conventional pressure-contact terminal, a lower end portion 5a of each of the pressure-contact blades 5 is formed in a waved shape and the waved lower end portion 5a is connected to a bottom wall portion 6 of the present pressure-contact terminal. The waved, lower end portions 5a can be flexed and restored when the covered electric wire is pressure-contacted with the pressure-contact blades 5, thereby preventing the pressure-contact blades 5 from spreading out.
Now, FIG. 7 is a developed view of the present conventional pressure-contact terminal, showing how to manufacture the same; that is, the pressure-contact terminal shown in FIG. 6 can be manufactured by punching out a conductive plate material by a press and then bending the punched-out plate. In FIG. 7, reference character 7 designates the portion of the conductive plate where the pressure-contact blades 5 is made, and 8 designates the portion of the conductive plate where the waved lower end portions of the waved pressure-contact blades 5 is made.
Now, FIGS. 8 and 9 respectively show another conventional pressure-contact terminal, in which two pressure-contact blades 5 are respectively formed in the two ends of each of a pair of right and left side wall portions 4. These pressure-contact blades 5 are formed by bending the two end portions of each of the side wall portions 4. There are recessed portions 4a formed in the lower end portion of each of the side wall portions 4 to provide a strength, thereby preventing the side wall portions 4 from spreading out. According to this conventional pressure-contact terminal, as shown in FIG. 9, when a covered electric wire 9 is inserted, the pressure-contact blades 5 bite the covered electric wire 9 for connection thereto, and, by clamping a clamping portion 3 of the present pressure-contact terminal, the covered electric wire 9 is fixed.
As described above, in either of the conventional pressure-contact terminals, there is necessary a structure which can prevent the pressure-contact blades 5 from spreading out easily, with the result that the shape of the pressure-contact terminal is complicated. This not only increases the number of pressing steps of manufacturing the pressure-contact terminal but also makes a metal mold complicated in shape, which results in the troublesome manufacture of the pressure-contact terminal. Also, even use of such a complicated structure is not always be sure to prevent the pressure-contact blades 5 from spreading out, and thus there still remains a fear that the contact of the pressure-contact terminal with the covered electric wire can be made poor due to the spread-out pressure-contact blades thereof, thereby worsening the electric reliability of the pressure-contact terminal.